Circuit interrupter



Sept. 16, 1952 B. c. WEBSTER 2,611,055

CIRCUIT INTERRUPTER Filed Sept. 27. 1949 2 SHEETS-SHEET 2 Fig.6.

Fig.4. 7|

WITNESSES: INVENTOR fi Benljagmin C. wexbstler.

Patented Sept. 16, 1952 CIRCUIT INTERRUPTER Benjamin C. Webster, Southport, Conn., assignor to Westinghouse Electric Corporation,

East

Pittsburgh, Pa., a corporation of Pennsylvania Application September 27, 1949, Serial No. 117,970

18 Claims. 1

The invention relates to circuit interrupters, and more particularly to manually and automatically operable low voltage circuit breakers for controlling motor, lighting and other small and moderate power electric circuits.

, An object of the inventionis to provide an improved. circuit breaker of compact design which will fit in a standard outlet box and which has an interrupting capacity of much larger breakers.

Another object of the invention is to provide an improved double pole circuit breaker wherein tthe operating mechanism is disposed in a central compartment and the contacts for the two poles are disposed in separate compartments disposed one oneach side of the central compartment.

Another object of the invention is to provide a circuit breaker according to the preceding paragraphs in which each pole is provided with double break contacts.

Another object of the invention is to provide a small compact circuit breaker which may readily be assembled as a single or double pole breaker.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, both-asto construction and operation, together with additional objects and advantages thereof will be best understood from the following detailed description thereof when read in conjunction with the accompanying drawings.

In said drawings:

Figure 1 is a top plan view of a circuit breaker constructed in accordance with the invention,

Fig. 2 is a vertical elevational view between the central housing members substantially along line .III'III of Fig. 1 and showing the contact structure of one pole of the breaker,

Fig. 4 is a vertical transverse sectional view taken on line IV-IV of Fig. 2 and looking in the direction of the arrows,

Fig. 5 is a vertical elevational view similar to .Fig. 2 but showing the breaker operating mechanism in the tripped open-position,

Fig. 6 is a top plan view of one of the movable contact elements, and

Fig. '7 is a vertical sectional view through a modified inner housing member used when the breaker is assembled as a single pole breaker.

As shown in the drawings, the circuit breaker ,comprises generally a housing indicated at H which is divided into four parts for assembly purposes, stationary contacts l3 and I5 (Fig. 3), movable contact means M, an operating mechanism indicated generally at H! (Figs. 2, 4 and 5) and a thermal trip device indicated generally at 2|. 7

The housing (Figs. 1 and 4) consists of two central portions 23 and 25 and two outerportions 21 and 29 all of molded insulating material. The two central portions 23-25 of the housing are provided with internal surfaces and recesses for receiving and supporting the several parts of the operating mechanism l9 and the trip device 2|, and are provided with recesses and surfaces on the outside thereof for cooperating with similar recesses and surfaces on the inner sides of the outer portions 21-29 of the housing for receiving and supporting the stationary contacts |3 -|5 and the movable contacts IT.

The several portions of the housing are held rigidly together by means of three rivets or bolts 3| (Figs. 2, 3 and 5) which extend through openings in the several portions of the housing and are riveted over against the housing or have nuts (not shown) threadedly engaging the ends thereof.

In order to mount the circuit breaker in an outlet box 32 (Fig. 3), there are provided a pair of brackets 33 one disposed at each end of the breaker housing. Each of the brackets 33 is provided with a pair of downwardly extending ears .35 disposed in recesses 31 (Fig. 1) formed on opposite sides of the inner housing members 2325. The ears 35 are provided with openings through which the upper rivets or bolts 3| (Figs. 2, 3 and 5) extend to rigidly secure the housing to the brackets 33. The brackets 33 are provided with threaded openings 30 (Fig. 1) to receive screws 34 .(Fig. 3) for mounting a cover plate 36 thereon.

The contact structure for one pole of the breaker is clearly shown in Fig. 3 of the drawings. Since the contact structures for each of the two poles of the breaker are alike, only the one shown in Fig. 3 will be described. The stationary contact l3 (Fig. 3) is rigidly secured to the inner end of a conducting strap 39 disposed in cooperating recesses in the housing portions 25-29 and having its upper end formed over to receive a terminal screw 4|. The stationary contact I5 is rigidly secured to the inner end of a conducting strap 43 which extends downwardly from the contact l5 and then to the right and upwardly in an angular channel 45 formed in the portions 25-29 of the housing (see also Fig. 4). At the upper end (Fig. 3) the strap 43 is formed over as shown to threadedly receive a terminal screw 41 housing member to effect opening and. closing, 7

of the contacts and is held in place by the housing member 29. Springs 57 are compressed. be. tween the edge of the slidable; member 53 and the: bridging member $9 to provide contact pressure in the closed position of the movablecontact. de-. vice. It will be noted that there is a projection 59 (Fig. 3) molded integral with the housing portion 25 extending inwardly between the stationary contacts l3 and '51 and cooperating with. a matching projection (not shown). onfthe-housing portion 29 to preventfiashover'betwe'en. the stationary contacts upona, circuitjinterrupting operation. The bridging member 59 is formed inwardly as. at 'd! to. provide clearance for.- the projectionig. and the formed portion. Sli of the bridging. memberi's. provided with a. vertical slot 62. (Fig.3.). topermit freemovement-of the slid able switch'member 5.3 relative thereto. in. closing directioni Both of the. movable contact. means. are moved back and forth in their respective compartments to. open and close. the contacts by means of an actuator. 63 which forms part'oi' the operating 9 upon operation of the actuator 63 to open and closed positions. V

In addition toythe actuator 63, the operating mechanism. includes an operating handle .H',v a releasable member 53' and an overcenter spring 75' tensionedbetween' the actuator 63 and the releasable member- 73.

The operating; handle it is pivotally mounted on trunnions' W- supported in opposed openings in the housing portions 23 and 25 and is provided with spaced inwardly extending arms 'iemolded integral therewith. The actuator 53. has a pair of spaced upwardly extending legs 81 having laterally extending projections 82 thereon which are seated in the bottoms of slots '83: provided in the inner ends of the levers 19 and are held place by the overcenter spring 15.

The left-hand end (Figs. 2 and 5) of the releasable member: 13' is bifurcated to clear the overcenter spring T5. (Fig. 3.)v in the closed position and each of the legs thereof is provided with an outwardly extending, projection: 85 pivota'lly supported. inrecesses in thei'nnerwalls ofthe housing portions 23-25;. The releasable mem. her it is provided at its free end with a latch portion 8'!- Whi'ch normally engages a latch portion ceof a bimetal element 9-! to releasably restrain the releasable member 13 in'the position in-which. it appears in Fig. 2;.

= The bimetal element M has a mounting foot. or

4 portion 93 (Figs. 2 and 5) formed at right angles to the body portion thereof. The foot 93 of the bimetal element is disposed in a horizontal recess 55 formed. in the housing portions 23-25 of the housing. The extreme left end of the mounting foot 93 of the bimetal element is formed outwardly at right angles as at 91 and is seated against the left wall of the recess 95.. in'the portions 23-25 of the housing to properly locate the bimetal element. The mounting foot 93 of the bimetal element is rigidly clamped against the upper wall of the recess 95 by means of bar 96 and a headed screw 99 extending upwardly through openings in the bar 96 and the portion 93 of. the bimetal element and disposed in a recess Izill: (Figs. 2;. 4= and 5) formed in the portions ESP-25 of the housing. The inner end of the screw 99 threadedly' engages a nut ms disposed in'an enlarged portion of the recess 19!, thus clamping the mounting foot 93 of the bimetal elementagainst the upper wall of the recess-95. The. tripping characteristic of. the breaker is adjusted by means of. an adjusting ,screw {[05 (Figs. 2. and.5) vthreadedly engaging. .in.an.iop.ening in the bar 96. and havingv its inner endfen'ga'ging an angular portion 93. of" thefbim'etal By slightlyrotating. the screw 1.8.5, the. bimetal. ele: ment may be flexed; and the overlapof the latch 87- 89 adjusted to; vary the tripping, time of the breaker.

The circuit throughthe leftehand poleiFig. 4) of the breaker, orv the bottom pole asviewe'di in Fig.1, extends from the terminal, 4! (Fig, 3). through the conducting strap 39', stationary contact i3; movable contact IT and the bridging member 9,; lower: movable contact. H, stationary contact i5. conducting strap 33 to the terminal 4.7. The. contact structure for the. right-hand pole (Fig; 4) or upper pole (Fig; I) is the same as thatdescribed for the opposite pole, but the circuit extending through the upper pole (Fig. 1) of the breaker. is somewhat different since a heaterelementl! l (Figs. 1, 2 and 5).for' heating the; bimetal element'fil in response'to overload currents. is connected in series relation. in. the circuit through thispole of the breaker:

A' conductor strap (not shown); but. similar'to the conductor strap 53 (Fig. 3') upon which the stationarycontact r5 is mounted', isv provided, for the upper pole (Fig. 1) but this strap is connected to an intermediate terminal I [3 to which isalso connected an angular strap H5. The strap H5 extends through a slot H7 in the housing; portion 23- and one end of the-heaterelement H1 is electrically connected thereto. The other end of the heater element l l l is electrically connected to a conducting member 1 i9 (Figs. 2 and 5-) which is, in turn, secured by means of a screw l2'l to a conductor strap [23. The strap 1-23 extends outwardly through an opening in the wall of the housing portion 23 and is provided with a terminal screw 525 (Fig. 1) for connecting it in the electrical circuit. A sheet of insulating material i2"! (Figs. 2 and 5') is disposed in suitable slots in the housing members 23-25 to protect the housing against the heat of theheater element.

The circuit through the upper pole ;of the breaker (Fig. l.) is: traced as fol-lows: From the terminal it through the stationary and movable contacts to the intermediate terminal H31.'c'cnducting strap? tie", heater element i l' i conducting member i and; conducting stra-p 121i to the. terminal vbers 53 to the open position. 7 that the releasable member I3 has a pair of ears heater element and the compartment in which the heater element is mounted is normally covered by a member I29 of insulating material secured to the conducting member I I9.

\ 'Ihe heater element may readily be removed for inspection or for substituting an element of different rating by removing the screws H3 and I'll (Fig. 1) and lifting the heater element including the conductors H5 and H9 out of the housing.

The circuit breaker is operated to manually open the contacts by rotating the handle 'II in a clockwise direction about trunnions H from the on position (Fig. 2) to the off position. During this movement the pivots 82 for the actuator B3 are moved to the left of the line of action of the overcenter spring I5 whereupon the spring I5 rotates the actuator counterclockwise about its pivot 82with a snap action until it is arrested by projections 65 striking the righthand walls of the openings 51 in the housing members 23 and 25. The counterclockwise movement of the actuator 63, due to the projections 65 engaging the switch members 53, slides these members toward the right (Fig. 3) to the open position.

The contacts are closed by reverse operation of the mechanism. When the handle is rotated counterclockwise to the on position, the arms I9 thereon carry the upper end of the actuator 65 across to the right of the spring I5. When this happens, the spring I5 biases the actuator in a clockwise direction and immediately rotates the actuator clockwise to slide the switch members 53 toward the left and close the contacts with a snap action. In the closed position of the breaker, the projections 65 on the actuator do not engage the left-hand wall of the openings 61. The overcenter spring 15, in the closed position, biases the projections I55 on the actuator against the left wall of the cam slots 69 in the switch members 53 causing these members to compress the springs 51 to thereby provide contact pressure in the closed position of the switch members.

The circuit breaker is automatically tripped open in response to overload currents occurring in the circuit controlled by the breaker. Upon the occurrence of an overload current, the excessive current flowing through the heater element II I heats this element and consequently the bimetal element 9I. When heated a predetermined amount, the bimetal element 9| deflects toward the right (Fig. 2) and releases the releasable member I3, whereupon the over-center spring I5 rotates the releasable member in a clockwise direction about its pivot 85 from the position in which it appears in Fig. 2 to the Fig. 5 position, the clockwise movement of the releasable member being arrested by striking the bottom wall I35 of an opening I3I in a partition wall I39. The clockwise movement of the releasable member I3 carries the overcenter spring I5 across to the right of the pivot 82 of the actuator 63 and the spring I5 immediately snaps the actuator counterclockwise to the open position as shown in Fig. 5 to move the switch mem- It will be noted I formed thereon, the purpose of which is to positively initiate opening movement of the actuator B3 and the switch members during an "automatic opening operation. Referring to Fig.

ment 9|, the ears I4l strike formed portions I43 on the legs 8| of the actuator 63 and start it in opening direction. Thus the opening movement of the actuator 63 and the movable contact means are positively initiated. l

When the overcenter spring I5 passes to the right of the actuator pivot 82, it acts through the actuator to rotate the operating handle II in a clockwise direction to an intermediateindicating position (Fig; 5) where it is arrested in an intermediate position by engagement of the upper ends of thelegs BI of the-actuator 63 with the ears MI on the releasable member 13. This position of the'handle I I gives an indication that the breaker has been automatically tripped open.'

Before the breaker contacts can be closed fol lowing an automatic tripping operation, the mechanism must be reset and the releasable member I3 relatched. This is accomplished by rotating the operating handle II in a clockwise direction from its Fig. 5 position to the off position. During this movement of the handle II, the upper ends of the legs SI of the actuator acting through the ears I II rotate the releasable member I3 counterclockwise about pivots to effect reengagement of the latch portion 81 of the releasable member with the latch portion 89 of the bimetal element 9 I. Thereafter the breaker contacts are closed in the previously described manner by rotating the handle 'II counterclock wise to the on position.

The outer housing members 2! and 29 may be removed without disturbing the operating mechanism in order to inspect the contact means. With the breaker in the open position, the movable contacts may be removed and replaced without disturbing the operating mechanism by merely lifting the members 49-53 out of the housing. Also the stationary contacts may be removed and replaced by lifting the conducting straps 39 and 43 out of their respective recesses.

The breaker may be assembled as a single pole breaker by omitting one of the movable contact members without in any way unbalancing the operating mechanism. When assembled as a single pole breaker the outer. housing member 29 may be omitted and a modified inner housing member 25 (Fig. 7) substituted for the inner housing member 25. Also the corresponding end 55 of the actuator is removed or a modification 63 (Fig. 7) of the actuator is substituted for the actuator 63. The operating mechanismis readily accessible for inspection and adjustment by removing either the housing members 25 .29 or 232'I.

While the invention has been disclosed in accordance with the provisions of the patent statutes, it is to be understood that various changes in the structural details thereof may be made without departing from some of th essential features of the invention.

I claim as my invention:

1. A circuit breaker comprising, in combination, a pair of separable housing members co operating to form a first compartment, cooperating contact means, operating mechanism therefor including a manually operable operating member for manually operating said contact means, electroresponsive means operable in response to overload currents to effect automatic opening of said contact means, said housing members serving as a frame for said breaker and having cooperating recesses and surfaces in said first compartment for receiving and sup porting said operating mechanism, and an'outer housingmemher: cooperating with one of said pair of housing members to form a, second compartment disposed side by side with said first, compartment andhaving recessesand surfaces cooperating with recesses and: surfaces on said one of said pair-of-housing members tor receiving and, supporting said separable contact means.

2.. A circuit breakercomprising, in combination, a pair of'housing members, a set of relatively movable contact means, operating mechanism therefor, electroresponsive means operable response to overload currents to effect auto matio opening of said set of contact, means, said housing members forming a first compartment having recesses and surfaces for receiving and supporting said operating mechanism, and, a third'housing member cooperating with one of said pair of housing members to' form a separate compartment disposed side by side with saidfirst compartment andhaving recesses and surfaces for receiving and supporting'said set of relatively movable contact means.

v3'. A circuit breaker comprising a plurality of sets of stationaryand movable contact means, operating means for said contact means in cluding an actuator for opening and closing said contact means, current responsive means responsive to overload currents to effect automatic opening of said contact means, an insulated housing for said breaker comprisinga pair of inner housing members cooperating to form a central compartment having recesses and surtacos for receiving and supporting said operating means, outer housing members cooperating with the adjacentinner housing members to form outer compartments each having recesses and surfaces for receiving and supporting one of said sets of relatively movable contact means, and projections on said actuator extending into each of said outer compartments for actuating the movable contact means disposed in said compartments." r a E. A, circuit breaker comprising a plurality of sets of spaced stationary contacts and cooperating movable contact means, operating mechanism for said movable contact means including an actuator operable ,to open and close said contact means and a, releasable member releasable to efi'ect automatic opening operation of. said actuator, trip means responsive to over load currents for eifecting release of said releasabl'e member, an insulating housing for said circuit breaker comprising a pair of inner housing members cooperating to form a central compartment for receiving saidv operating mechani'sm, said. centraI compartment being provided with recesses and surfaces for receiving and supporting the partsv of said operating mechanism without any of said parts being positively fastened to saicli housing members, a plurality of outer housing members one cooperating with each of said inner housing members to iorm compartments for receivingsaid sets of stati'onary and movable contact means, each of said outer compartments having recesses and surfaces for receiving and supporting one set of said spaced stationary contacts without said contacts being positively fastened'to said housing and also having recesses and surfaces for receiving and slidably supporting said movable contact" means, and said actuator having portions extending into said outer compartmentsfor separably' engaging and actuating said movable contact means.

5. A- circuit breaker comprising a plurality of sets of spaced stationary contact means, movable bridging contact means cooperating with each set of stationary'contact meansoperating-mechanism for said movable contactmeans including a manually operable operating member, a trip device including a thermally responsive bimetal element operable in response to overload currents to cause automatic opening of said contact means, separate terminals connected to said spaced stationary contact means for connecting the breaker in an electrical circuit, an insulating housing for said breaker comprising a plurality of separable housing members cooperating to form inner compartments for receiving said operating mechanism and said trip device, and also forming outer compartments for receiving said terminals, said sets of stationary contacts and their cooperating movable contact means, an actuator operable by said manually operable operating member and having portions extending into said outer compartments for engaging and simultaneously operatingsaid movable bridging contact means. a

6. A circuit breaker comprising a plurality of stationary contact means, cooperating movable contact means, operating mechanism therefor including an actuator for moving said movable contact means to open and close said contacts, a trip device responsive to overload currents to eiiect automatic opening of said contact means, an insulating housing for said circuit breaker comprising four separable members having joints between adjacent members, the two center housing members forming an. inner compartment for receiving and supporting said operating'mechanism and each of the center housing members cooperating with one of the outer housing members to form compartments for receiving and slidably supporting said movable contact means, and projections on said actuator extending laterally into said outer compartments and'engaging cam means on said movable contact means for slidably actuating said movable contact mean upon operation of said actuator. Y a

7. A circuit breaker comprising a plurality of pairs of spaced stationary contacts, cooperating movable contact means for each pair of stationary contacts including an insulating switch member having a cam slot therein. and a bridging contact member resiliently mounted on said switch member, operating mechanism for said movable contact means including an actuator, an insulating housing for said breaker compris ing a pair of inner housing members and a pair of outer housing members, said inner housing members cooperating to form a compartment having recesses and surfaces for receiving and supporting said operating mechanism, said outer housing members cooperating with said inner housing members to form outer compartments spaced laterally from said inner compartment and having surface and recesses for receiving and supporting said spaced stationary contact means in fixed position, said outer compartments each having surfaces and recesses forming channels for receiving and slidably supporting said movable switch members for movement in planes parallel to but spaced laterally from the plane of movement of said operating mechanism, and projections on said actuator extending laterally therefrom into said outer compartments and engaging in said cam slots for actuating said switch members to open and close said contact means. l

8, A circuit breaker comp-rising a plurality of pairs of spaced stationary contacts, cooperating movable contact means for each pair or stationary contacts including an insulating sliding switch member having a cam slot therein and a bridging contact member resiliently mounted on said switch member, operating mechanism for said movable contact means including a manual operating handle for manually opening and closing said contact means,. an actuator pivotally supported on said operating handle, a pivoted releasable member and an overcenter, spring tensioned between said releasable member and said actuator, circuit responsive means operable in response to overload currents for releasing said re-, leasable member to thereby effect automatic opening of said contact means, said movable switch members being spaced laterally one on each side of said operating mechanism and disposed for sliding movement in planes parallel to the plane of movement of said operating mechanism, and projections on said actuator extending laterally into engagement withsaid cam slots for reciprocably moving said switch members to move said bridging contact members into and out of engagement with the corresponding pair of stationary contacts. 7

9. A circuit breaker comprising spaced stationary contacts, a bridging contact member cooperating with said spaced stationary contacts, a slidable switch member of insulating material supporting said bridging contact member, operating mechanism including an actuator for moving said slidable switch member to open and close said contacts, a trip device responsive to overload currents to effect automatic opening movement of said slidable switch member, an insulating housing for said circuit breaker comprising a pair of separable members cooperating to form a main compartment for receiving and supporting said operating mechanism, a third separable member cooperating with one of said pair of separable members to form a second compartment for receiving and removably supporting said stationary contacts andfor receiving and removably supporting said slidable switch mem-, her, and a projection, on said actuator extending laterally into said second compartment and separably engaging cam means on said slidable switch member for actuating said movable con-, tacts upon operation of said actuator, said stationary contacts and said slidable switch member being removable without disturbing said opcrating mechanism and said trip device.

-10.;A circuit breaker comprifng stationary contacts, a cooperating bridging contact memher, a slidable switch 1 member supportin Said bridging contact member, said slidable switch member having a cam slot therein, operating mechanism including an actuator for moving said slidable switch member to open and close said contacts, a trip device responsive to overload currents to effect automatic opening movement or said slidable switch member, an insulating housing for said circuit breaker comprising a pair of separablev members cooperating to form a main compartment for receiving and supporting said operating mechanism, athird separable member cooperating with one of 'said pairs of separable members to form a second compartment for receiving and removably supporting said stationary contacts and for removably supporting said slidable switch member, and a projection on said actuator extending into said second compartment and separably er-gagingsaid cam slot for actuating said slidable switch mem- 10 bers upon operation of said actuator, said slidable switch member together with said bridging contact member being removable without disengaging any connection with said actuator.

11. A multi-pole circuit breaker comprising a housing of molded insulating material, said housing comprising a pair of inner members cooperating to form a central compartment and a pair of outer members cooperating with said inner members to form outer compartments spaced laterally from said inner compartments, contact means including a plurality of sets of spaced stationary contacts one set being disposed in each of said outer compartments, and a movable bridging switch member slidably disposed in each of said outer compartments cooperating with the corresponding set of spaced stationary contacts, operatin mechanism including an actuator disposed in .said central compartment and. operable to effect reciprocal sliding movementof said switch members to open and close said contact means, projections on said actuator extending laterally in opposite directions into said outer compartments and separably engaging said switch members to actuate said switch members, and matching projections molded integral with said inner and outer housing members and extending between said spaced stationary contacts to prevent flashover.

12. A circuit breaker comprising relatively movable contacts, operating mechanism for opening and closing, said contacts, a thermally responsive bimetal element having a main body portion operable in response to overload currents to cause automatic opening of said contacts, a mounting foot formed at right angles to said main body portion, said bimetal element having an angular portion between said mounting foot and said main body portion, an insulating housing for said breaker including two separable members serving jointly as aframe for said operatin mechanism, said housing members having corresponding recesses and surfaces for jointly receiving and supporting said operating mechanism, said housing members jointly forming a recess for receivingsaid mounting foot and locating said bimetal element, a support member for supporting said bimetal element, fastening means for securing said support member and said mounting foot to said separable housing members, and adjusting means mounted in said support member and engaging said angular por-..

tion of said bimetal element for adjusting the main body portion of said bimetal element.

13. A circuit breaker comprising spaced stationary contacts and cooperating movable contact means, operating mechanism for said movable contact means including an actuator operable to open and close said contact means and a releasable member releasable to effect automatic opening operation of said actuator, trip means responsive to overload currents for effectin release of said releasable member, an insulating housing for said circuit breaker comprising a p'airof housing members cooperating to form a main compartment for receiving said operating mechanism, said main compartment being provided with recesses and surfaces for receiving and supportin the parts of said operating mechanismwithout any of said parts being positively fastened to said housing members, an outer housing member cooperating with one of said main housing members to form a compartment for receiving said stationary and movable contact means, said outer compartment having rei ll cesses and surfaces for receiving and supporting said spaced stationary contacts without said contacts being positively fastened to said housing and also having recesses and surfaces for receiving and slidably supporting said movable contact means, and said actuator having a portion extending into said outer compartment for separably engaging and actuating said movable contact means.

'14. A circuit breaker comprising stationary contact means, cooperating movable contact means, operatingmechanisin including an'actuator for moving said movable contact means to open and close said contacts, a trip device responsive to overload currents to effect automatic opening of said contact means, an insulating housing for said circuit breaker comprising a pair of separable members cooperating to form a main compartment for receiving and supporting said operating mechanism, a third separable member cooperating with one of said pair of separable members to form a second compartment for receiving and supporting said stationary contact means and for receiving and slidably supporting said movable contact means, and a projection 'on said actuator extending laterally into said second compartment and engaging cam means on said movable contact means for slidably actuating said movable contact means upon op-' eration of said actuator.

15. A circuit breaker comprising spaced stationary contacts and cooperating movable contact means including an insulating switch member having a cam slot therein and'a bridging contact member resiliently mounted on said switch member, operating mechanism for said movable contact means including an actuator, an insulating housing for said breaker comprising a pair of main housing members and a third housing member, said main housing members cooperating to form a main compartment having recesses and surfaces for receiving and supporting said operating mechanism, said third housing member cooperating with one of said main housing members to form. asecond compartment spaced laterally from zsai'dlnain compartment and having recesses and surfaces for receiving and supporting said .spa'ced stationary contact means in fixedposition, said second compartment having recesses and surfaces forming channels for receiving and slidably supporting saidmovable switch member for movement in a plane parallel to but spaced laterally from the plane of movement of said operating mechanism, and a projection on said actuator extending laterally therefrom into said second compart ment and engaging in said cam'slot for actuating said switch member to open and close said "contact, means.

16, A circuit breaker *comprising spaced stationary contacts, cooperating movable contact means including an insulating sliding switch member having a cam slot therein and a bridging contact member resiliently mounted on said switch member, operating mechanism for said movable contact means including a manual operating handle for manually opening and closing said contact means, an actuator pivotally supported on said operatin handle, a pivoted releasable memberrand an overcenter spring tensioned between said releasable member and said actuator, current responsive means operable in response to overload currents for releasing said releasable member to thereby effect automatic opening of said contact means, said movable 12 switch member being spaced laterally to one side of said operating mechanism and disposed for sliding movement in aplane parallel to the plane of movement of said operating mechanism, and

a projection on said actuator extending laterally into engagement with said cam slot for reciprocably moving said switch member to move said bridgin contact member into and out of engagement with said spaced stationary contacts.

17. A circuit breaker comprising stationary contact means, cooperating movable contact means, operating mechanism including an actuator for'moving said movable contact means to open and close said contacts, a trip device responsive to overload currents to effect automatic opening of said contact means, an insulating housing for said circuit breaker comprising a pair of separable members cooperating toform a main compartment for receiving'and supporting, said operating. mechanism,- a third separable member cooperating with one of said pair of separable members to form a second compartment for receiving and removably supporting said stationary contact means and said movable contact means, a projection on said actuator extending laterally into said second compartment and separably engaging said movable contact means for actuating said movable contact meansupon operation of said actuator, and said movable-contact means being removable without disengaging any connection with said operating mechanism.

'18, A circuit breaker comprising spaced stationary contacts and cooperating movable contact means including an insulating switch member having a cam slot therein and a bridging contact member-resiliently mounted on said switch member, operating mechanism for said movable con-tact means including an actuator, an insulating housing for said breaker-comprising a pair of main housing members and a third housing member, said main housing members cooperating to form a main compartment having recesses and surfaces for receiving and supporting said operatingmechanism, said third housing member cooperating with one of said main housing members to arms second compartment spaced later ally from s'aidm'ain compartment and having recesses and surfaces for receiving and removably supporting said spaced stationary contact means in fixed position, said second compartment having recesses and surfaces forming channels for receiving and removably supporting said movable switch member for movement in a plane parallel to but spaced laterally from'the plane of movement' of said operating mechanism, a projection on said actuator extending into said second-compartment and separably engaging in said cam slot for actuating said switch member to open and close-said contact means, and said switch members together with "said bridging contact member being removable without dis-engaging any connection with said operating mechanism;

BENJAlHIN C. WEBSTER.

REFERENCES CITED The following references are of record in the file of this patent: v

I UNITED STATES PATENTS v Date Number Name 1,942,115 Milone Jan. 2, 1934 2,185,525 Sachs Jan. 2, 1940 2,242,167 Bentley May 13, 1941 7 Taylor Feb. 27, 194-5 

